The Metabolizable Energy Content of Rapeseed Oils and Rapeseed Oil Foots and the Effect of Blending with Other Fats

Abstract

Experiments were carried out with chicks and turkey poults to determine the metabolizable energy content of rapeseed oils and rapeseed oil foots and the effect on energy utilization of blending these oils with tallow and mixtures of saturated fatty acids.In general, low erucic acid rapeseed oil (Oro variety) gave superior growth and feed efficiency and was as high or higher in M.E. value as compared with regular Brassica campestris rapeseed oil. While rapeseed oils and rapeseed oil foots were reasonably well utilized as a source of energy by chicks and poults, there was a synergistic effect in energy utilization when these oils were mixed with tallow. Thus the energy content of the mixture of rapeseed oil and tallow was greater than that anticipated from the fats fed singly. The synergism was less for poults than for chicks, probably because poults utilized rapeseed oils to a greater extent than chicks when fed without mixing.Chicks fed mixtures made up chiefly of palmitic and stearic acids, along with rapeseed oil or rapeseed foots, demonstrated similar synergism in fat utilization to those fed tallow with rapeseed oil. These results confirm and extend previous findings indicating that rapeseed oil is imbalanced in fatty acid make-up for maximum absorption, being too low in the long chain saturated fatty acids, palmitic and stearic. While synergism in energy utilization was also demonstrated when low erucic acid oil was mixed with tallow, the effect was less than with regular Brassica campestris oil. This is probably explained by the fact that the low erucic acid oil is better utilized when fed alone than the regular rapeseed oil.